The present invention relates to apparatus for applying labels to successive commodities, especially to substantially brick-shaped prismatic commodities or items, such as packs for cigarettes, cigars or cigarillos. More particularly, the invention relates to improvements in apparatus for applying adhesive labels or analogous pieces of flexible sheet material to selected portions of substantially prismatic items while the items move, either continuously or stepwise. Typical examples of labels which can be applied in the apparatus of the present invention are revenue labels which are glued across the front or top end faces of soft packs or hard packs (including hinged-lid or flip-top packs) for plain or filter tipped smokers' products.
Label applying apparatus normally form integral parts of packing machines for rod-shaped smokers' products (hereinafter called cigarettes for short). It is also known to install label applying apparatus between a packing machine and a machine which provides cigarette packs or the like with transparent or translucent outer envelopes consisting of cellophane or other plastic material. In many instances, such transparent outer envelopes embody customary tear strips to allow for rapid removal of outer envelopes and afford access to the one or the other end of the pack. In the case of flip-top packs, revenue labels are applied in such a way that a properly applied label must be destroyed before the user can pivot the hinged lid of the pack to open position.
The labels are relatively small, long and narrow, and they are applied to the packs in such a way that the central portion of a properly applied label overlies and adheres to the front end face of the pack while the end portions of the label overlie and are bonded to the adjacent (narrower or wider) lateral surfaces of the respective pack. In heretofore known label applying apparatus, the central portion of a label is attached to the front end face of an oncoming pack in a first step, and the end portions of the label are thereupon folded over the adjacent lateral surfaces of the pack by discrete folding instrumentalities. When the pack is a so-called soft pack, the label normally extends across the width of the front end face of the pack and its end portions are bonded to the adjacent wide lateral surfaces, normally at an angle of 90 degrees to the central portion of the label. When the packs are flip-top packs, the label is applied lengthwise of the top face of the lid and its end portions overlie and adhere to the narrow lateral surfaces of the pack.
The fact that the labels (especially revenue labels) are elongated contributes to complexity of the apparatus. Conventional apparatus include several conveyors one of which receives labels from a magazine or an analogous source of stacked labels and another of which places the central portions of successive labels into the path of oncoming packs. The end portions of the label are thereupon flexed to contact and adhere to the corresponding lateral surfaces. Such apparatus operate properly as long as the speed of the machine which supplies packs is below a certain limit. However, the speed of modern packing machines is so high that conventional label applicators cannot furnish and attach labels with the required degree of accuracy. Furthermore, many presently known high-speed packing machines for cigarettes or the like are about to be replaced with machines whose output is still higher. Consequently, there exists an urgent need for apparatus which can apply labels with a requisite degree of accuracy even if the speed at which the items must be labelled is a multiple of the speed which is required to apply labels to cigarette packs at the rate they issue from the majority of presently used packing machines. In the absence of a labelling apparatus which operates satisfactorily while a machine turns out say 400 packs per minute, the output of the packing machine must be reduced on the sole ground that the labelling apparatus is incapable of applying labels at the required rate.